Lifespan and Causes of Death in the Irish Wolfhound - Vetsuisse ...

3.11.1.3 Diagnosis
In affected animals, direct and consensual pupillary reflexes are impaired or absent.
During ophthalmoscopic examination, tapetal hyperreflectivity and/or nontapetal
depigmentation as well as retinal blood vessel attenuation and optic nerve atrophy
may be found. Both eyes are affected symmetrically.
Concerning differential diagnosis, PRA can be differentiated from other possible
causes of slowly progressive vision loss, such as cataracts, retinal scarring,
pigmentation or oedema, posterior uveitis etc. by ophthalmoscopy. Experimentally,
severe vitamin A and E deficiency has been shown to cause retinal degeneration in
dogs (Smith and Miller 2004).
3.11.1.4 Therapy
The disease is currently incurable and its progress unstoppable. Blind dogs should
be kept in a familiar environment and only walked on a leash. Practical suggestions
to improve quality of life include avoiding to change the position of furniture, using
dog toys that produce sound, and applying perfume to the pieces of furniture to help
the dogs identify their position (Smith and Miller 2004).
3.11.1.5 Prognosis
Affected animals will gradually and irreversibly turn completely blind. Nevertheless,
properly managed dogs have a normal life expectancy, unless they have to be
euthanised due to an inability to adapt to blindness.
3.11.2 Epizootology
Very little information on incidence and prevalence of PRA in the Wolfhound
population is available. It seems that only 4 new cases were registered with the Irish
Wolfhound Foundation during the past 10 years, with roughly 4'000 Wolfhounds
registered per year (Janis, personal communication). On the other hand, it is quite
probable that there are additional unreported cases. Nevertheless, the incidence of
PRA in Wolfhounds seems to be low at the moment.
3.11.3 Heredity and Control Measures
While a mutation in the rom-1 structural gene has been excluded as the cause for
PRA (Gould, Petersen-Jones et al. 1997), the exact molecular genetic base of the
disease in Irish Wolfhounds remains unknown. A simple autosomal recessive mode
of inheritance has been postulated; recommended control measures are thus not to
breed known carriers (parents of affected offspring) and full siblings of affected dogs
(2/3 risk of being a carrier). A lay article available on the internet includes a list of
presumed carriers (Thornton 2005).
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